Yes, I tried
I have exactly your configuration: Treo + Minisd Spectec + Skype.
Using Skype over Wi-Fi was only a partial success.
In fact I could chat (of course) and making calls to other Skype users. However during some of those phone calls I could not hear the voice of the person I was talking to (and he couldn't either).
The real disaster is calling traditional phone: in such a case, call is sent and the called phone starts ringing.
At that point Treo has already crashed (need a soft-reset) and traditional phone continues ringing uncontrolled(!)
Furthermore, if Treo goes to sleep with wi-fi working, when it wakes up, card is only seemingly working but will work again only with reinsertion of the card.
I blame it on Spectec driver.
Can someone help?